Troubleshooting Tip: Resolving IS-IS and BGP Parse Error Alarms on FortiGate

[adhawan]

Description	This article describes the steps to troubleshoot and resolve IS-IS and BGP parse error alarms on FortiGate devices. The alarms may appear after a firmware upgrade, and the cause can be related to neighbouring devices sending unexpected or malformed IS-IS packets.
Scope	FortiGate.
Solution	To resolve the IS-IS and BGP parse error alarms on FortiGate, follow these steps: Check the logs for any routing events or errors related to IS-IS or BGP. Enable debugging for IS-IS to gather more information about the issue: FGT # diagnose ip router isis level info FGT # diagnose ip router isis all enable FGT # diagnose debug enable To stop the debug-type output : FGT # diagnose ip router isis level none Verify if any neighbouring devices on the network are running IS-IS or BGP and may be sending unexpected or malformed packets to the FortiGate interfaces. Check the FortiGate configuration to ensure that there are no incorrect or missing routes. Reboot the FortiGate device to see if the alarms clear. If the alarms persist, check the system event logs for any other related errors or warnings. If continuing to experience issues, refer to the FortiGate documentation for additional troubleshooting and configuration guidance: Technical Tip: FortiGate IS-IS configuration example (ISIS)